Coffee Extraction Calculator

How It Works

Coffee extraction yield measures what percentage of your ground coffee dissolved into the water during brewing. The formula is:

Extraction % = (Beverage Weight × TDS%) / Coffee Dose × 100

Where:

• Beverage Weight = total liquid in your cup (in grams or ml, since water ≈ 1g/ml)
• TDS = Total Dissolved Solids, measured with a refractometer (typically 1.0-1.6% for filter coffee)
• Coffee Dose = weight of dry ground coffee used

The Specialty Coffee Association (SCA) established the "Gold Cup" standard: an extraction yield between 18% and 22% produces the best balance of flavors for most people. Below 18% tends to taste sour, thin, and underdeveloped. Above 22% typically tastes bitter, astringent, and harsh.

How to Use This Calculator

1. Weigh your coffee dose before grinding (e.g., 18g for a V60 pour-over)
2. Weigh your finished beverage after brewing (e.g., 250ml)
3. Measure TDS with a refractometer — let the coffee cool to room temperature first for accurate readings
4. Enter all three values and the calculator instantly shows your extraction percentage
5. Check the zone indicator — green means Gold Cup, yellow means under-extracted, red means over-extracted
6. Follow suggestions to adjust your next brew if needed

Tips & Safety Notes

• Let coffee cool to 20-25°C before measuring TDS — hot coffee gives inaccurate refractometer readings.
• Always zero/calibrate your refractometer with distilled water before measuring.
• The "Gold Cup" range is a guideline, not an absolute rule. Some light-roast specialty coffees taste great at 20-23%, while some dark roasts are better at 17-19%.
• Brew ratio (dose:water) affects both strength (TDS) and extraction independently. A 1:16 ratio is a common starting point.
• If you don't have a refractometer, you can estimate based on taste: sour = under-extracted, bitter = over-extracted, balanced sweet = likely in the zone.

FAQ

What is a good coffee extraction percentage?

The SCA Gold Cup standard recommends 18-22% extraction yield. Below 18% is under-extracted (sour, thin, lacking sweetness), above 22% is over-extracted (bitter, astringent, dry). Most specialty baristas aim for 19-21% as the sweet spot.

How do I measure TDS for coffee?

TDS (Total Dissolved Solids) is measured using a digital refractometer designed for coffee, such as the VST LAB Coffee III or Atago PAL-COFFEE. Place a few drops of brewed coffee on the lens after cooling to room temperature, and read the percentage (typically 1.0-1.6% for filter coffee, 8-12% for espresso).

What affects coffee extraction rate?

The main variables are: grind size (finer = higher extraction), water temperature (hotter = higher extraction, aim for 92-96°C), brew time (longer contact = higher extraction), and agitation (stirring or turbulence increases extraction). The coffee-to-water ratio affects strength but also impacts extraction.

Does brew method affect extraction targets?

Yes. Espresso typically targets 18-22% extraction at 8-12% TDS (much more concentrated). Immersion methods (French press) may extract slightly less efficiently than percolation (pour-over). The Gold Cup range applies primarily to filter/drip coffee.

Why does my refractometer reading seem inaccurate after fermentation?

If you're measuring cold brew or any coffee that's been sitting, dissolved CO₂ and temperature variations can affect refractometer readings. Always let coffee reach room temperature (20-25°C) and gently stir to release CO₂ before measuring.

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Last reviewed: June 2026